Short answer. Unless the Constitution or a law says otherwise, it borrows from the Court of Appeals. Rule 125, Section 1 provides that the procedure in the Supreme Court, in both original and appealed cases, shall be the same as in the Court of Appeals — subject to any contrary provision of the Constitution or statute.
What the law says
Unless otherwise provided by the Constitution or by law, the procedure in the Supreme Court in original and in appealed cases shall be the same as in the Court of Appeals.
Rule 125, Section 1 — Uniform Procedure. Read the full provision →
A default rule of borrowed procedure
Rather than writing out a separate, freestanding set of procedural steps for the Supreme Court, Section 1 adopts the Court of Appeals' procedure as the Supreme Court's default, both for original cases the Supreme Court hears directly and for cases that reach it on appeal. This applies whether the case reaches the Supreme Court as an original petition the Court hears directly or as an appeal from a lower court's ruling.
The Constitution and statute can override the default
The rule opens with 'unless otherwise provided by the Constitution or by law,' making clear this borrowed procedure yields wherever the Constitution or a specific statute prescribes something different for the Supreme Court. Rule 125 fills the gaps; it does not override higher sources of procedural law. A specific statute governing a particular kind of case, for instance, can prescribe its own distinct procedure that supersedes this default borrowing rule.
Why this simplifies practice before the Supreme Court
Because the default procedure tracks the Court of Appeals, practitioners already familiar with Court of Appeals practice — briefs, motions, timelines — are not starting from scratch when a criminal case reaches the Supreme Court. The continuity reduces the need for an entirely separate procedural rulebook at the highest level. The default also keeps the rules themselves shorter and more coherent, since Rule 125 need not restate procedural mechanics that Court of Appeals practice already covers.
What this default does not resolve
Borrowing Court of Appeals procedure answers how the Supreme Court proceeds mechanically — filing, motions, timelines — but it does not itself decide substantive questions like which cases the Supreme Court may properly hear in the first place, or what standard of review applies once a case is before it. Those questions are answered elsewhere, in the Constitution, in specific statutes, and in the Court's own rules governing modes of appeal, with Section 1 filling only the procedural gap left once those other sources have spoken. Practitioners should also keep in mind that this default covers procedure, not substantive criminal law; the Court of Appeals' own procedural rules can themselves be modified by later circulars or amendments, so counsel still needs to confirm the current version of the borrowed procedure rather than assume it remains static over time.